Rubber composites (such as pneumatic tires, belts and hoses) commonly use brass-plated steel wires for reinforcement. Brass-plated steel wires have provided good results in general as regards to adhesion but has shown insufficient protection in respect to corrosion. It is known that, during vulcanization of the composite, the copper in the brass reacts with the available sulfur in the rubber and creates a thin layer of copper sulfide which forms an interface between the rubber and the wire therefore providing good initial adhesion of the rubber to the brass. Unfortunately, with aging of the rubber/copper bonding, there is a deterioration in the thin layer owing to a corrosion problem and loss of adhesion.
Efforts have been made to use zinc-coated wires because of its tendency to be more corrosion-resistant. Unfortunately, there is insufficient adhesion properties to rubber in many composite applications, such as tires. Therefore, there exists a need to improve the rubber to zinc-coated wire adhesion properties because prior attempts required very high amounts of cobalt salts or needed lead oxide and avoidance of such high levels of cobalt and use of lead oxide is preferred.